JP2005086599A - Decoding device, decoding program, and decoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To guarantee data transfer without delaying the data transfer after the expansion of image data subjected to compression coding by using a variable length code even if the data are decoded and expanded, also attain low power consumption. <P>SOLUTION: A decoding device is composed of an expander 2 for receiving the image data subjected to compression coding and decoding the received data; a clock number detecting means 5 for detecting the number of clocks adaptable to decoding in the expander 2 for unit region of the image data; a velocity control means 6 for changing, for each unit region, the number of operating clocks when the expander 2 decodes the data on the basis of the number of clocks detected by the means 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a decoding apparatus, a decoding program, and a decoding method for decoding image data that has been compression-encoded and reproducing image data before compression-encoding or substantially the same image data.

For example, in a copying machine, a printer device, etc., after encoding the image data to be processed and compressing the data amount, the compressed data obtained by the compression is decoded and decompressed and printed out. A series of processes are performed. Such a series of processing is generally performed not only in copying machines and printer apparatuses but also in information processing apparatuses and communication apparatuses as long as it handles image data. In many cases, encoding of image data that falls within a predetermined code amount is required due to the communication capability for transmission and reception.
For this reason, when encoding image data, it has been proposed to perform entropy encoding using a variable-length code in order to perform encoding so as to be within a predetermined code amount (for example, Patent Document 1). If a variable-length code is used, among the image data (a set of data values) to be processed, a data value having a high appearance probability is converted into encoded data having a short code length, and a data value having a low appearance probability is converted. This is because by converting this into encoded data having a long code length, the encoding efficiency can be increased and compact encoding can be realized.

JP-A-5-3550

Incidentally, in recent years, it has been desired for a copying machine, a printer device, and the like to improve the productivity of print output by increasing the number of sheets processed per hour.
In order to realize this, it is necessary not only to increase the speed of the printer engine that performs print output but also to perform an operation in which the printer engine performs print output while decompressing the compressed data, for example. However, if a variable length code is used when encoding image data, the code length is not always constant. For this reason, there is a possibility that the decompression of the compressed data by the decompressor may not be in time and the printer engine waits for the print output. Therefore, in order to improve the productivity of print output, the decompressor performs high-speed operation based on the worst condition so that the decompression by the decompressor is in time even under the worst condition with the longest code length. Therefore, it is necessary to guarantee data transfer from the decompressor to the printer engine.
On the other hand, there is a demand for low power consumption for copying machines, printers, and the like. However, in order to guarantee the data transfer from the decompressor to the printer engine, if the decompressor tries to perform high-speed operation, the circuit size of the decompressor and the operation clock signal increase in frequency due to the high-speed operation. This is necessary, leading to factors that hinder low power consumption.

  Therefore, the present invention guarantees data transfer without delaying the data transfer after the decompression even when the image data compressed and encoded using the variable length code is decoded and decompressed. It is an object of the present invention to provide a decoding device, a decoding program, and a decoding method that can be obtained and achieve low power consumption.

  The present invention provides a decoding device devised to achieve the above object, a decompressor that receives and decodes compressed and encoded image data, and the decompressor for each unit area of the image data. The number of clocks detecting means for detecting the number of clocks adapted for decoding in the above, and the number of operating clocks when the decompressor performs decoding based on the number of clocks detected by the number of clocks detecting means for each unit area And a speed control means for changing.

  Further, the present invention provides a decoding program devised to achieve the above object, a computer receiving decompression means for receiving compression-encoded image data and decoding it, and a unit area of the image data The number of clocks detecting means for detecting the number of clocks adapted for decoding by the decompressor every time, and the number of operating clocks when the decompressor performs decoding based on the number of clocks detected by the clock number detecting means It is made to function as a speed control means which changes for every said unit area | region.

  Further, the present invention is a decoding method for receiving the compression-encoded image data by the decoding method devised to achieve the above object, and decoding it with an expander, A clock number detection step for detecting the number of clocks adapted to decoding by the decompressor for each unit area of image data, and when the decompressor performs decoding based on the clock number detected in the clock number detection step And a speed control step of changing the number of operating clocks for each unit area.

In the decoding device, the decoding program, and the decoding method according to the above procedure, the number of clocks adapted to decoding by the decompressor or the decompressing means is detected for each unit area of the image data, and the detected clocks are detected. Based on the number, the number of operation clocks when the decompressor or decompression means performs decoding is changed for each unit area. Accordingly, the decompressor or decompression means operates for each unit area while following the number of clocks adapted to decoding the unit area.
The unit area here is a predetermined pixel area constituting the image data, and corresponds to an area such as a block unit, a line unit, or a band unit. The number of clocks adapted for decoding refers to the minimum number of operating clocks in the decompressor or decompression means necessary to prevent delaying the processing after the decoding.
From these, according to the decoding device and decoding program of the above configuration, and the decoding method of the above procedure, even if the image data to be processed is compression-coded using a variable length code, For region units that mainly consist of short code length data and require less time for decoding, the number of operation clocks is reduced, and for region units that mainly consist of long code length data and require much time for decoding, It is possible to increase the number of operating clocks.

  According to the decoding device, the decoding program, and the decoding method of the present invention, since decoding is performed based on the number of clocks adapted to decoding of each unit area for each unit area of image data, it takes time, for example. By increasing the number of operation clocks for each area unit, it is possible to prevent data transfer after decompression due to the decoding from being delayed. That is, even when image data compressed and encoded using a variable-length code is decoded and decompressed, data transfer after the decompression can be guaranteed. Furthermore, it is possible to reduce the number of operating clocks, for example, for an area unit that requires less time for decoding. This also reduces power consumption when decoding and decompressing image data. Will be able to.

  Hereinafter, a decoding device, a decoding program, and a decoding method according to the present invention will be described with reference to the drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described. First, the configuration of the decoding device in the first embodiment will be described. The decoding apparatus described here decodes compression-encoded image data and reproduces image data before compression encoding or substantially the same image data. For example, a copying machine or printer It is used by being mounted on a device. However, as long as it handles image data, it is used on an information processing device such as a computer device having an image processing function, or a network system in which information processing devices are connected to each other by wire or wirelessly. Also good. Note that details of these various devices are well known, and a description thereof will be omitted here.

  FIG. 1 is a block diagram showing a schematic configuration example of a decoding apparatus according to the present invention. As shown in the figure, the decoding apparatus described here includes a memory 1, an expander 2, a first-in first-out memory (hereinafter simply referred to as "FIFO") 3, a printer engine 4, and the number of clocks. Detection means 5 and speed control means 6 are provided.

  The memory 1 includes a RAM (Random Access Memory), a hard disk device, and the like, and stores image data to be processed. It is assumed that the image data stored in the memory 1 is compressed and encoded by entropy encoding using a variable length code such as a Huffman code. However, the compression encoding method is not limited to this.

The decompressor 2 receives compression-encoded image data from the memory 1 and decodes it.
The FIFO 3 temporarily holds the image data decoded by the decompressor 2 and functions as a buffer memory between the decompressor 2 and the printer engine 4.
The printer engine 4 converts the image data received from the FIFO 3 into a visible image and prints it on recording paper.
The details of the decompressor 2, the FIFO 3, and the printer engine 4 are well known, and therefore the description thereof is omitted here.

  The number-of-clocks detection means 5 is the number of clocks (hereinafter simply referred to as “adaptive”) for image data received by the decompressor 2 from the memory 1 and decoded for each unit area of the image data. The number of clocks).

Here, the clock number detection means 5 will be described in more detail.
FIG. 2 is a block diagram showing a configuration example of the clock number detection means in the first embodiment of the present invention. As shown in the figure, the clock number detection means 5 described here includes an unpacking unit 11, a unit amount counter 12, a lookup table (hereinafter simply referred to as “LUT”) 13, and a clock number counting unit per unit. 14.

The unpack unit 11 divides image data to be processed, that is, image data compression-coded using a variable length code, for each code (symbol) constituting the image data.
The unit amount counter 12 detects a break for each unit area of image data to be processed. The unit area here is a predetermined pixel area constituting the image data, and corresponds to an area such as a block unit, a line unit, or a band unit. For example, it is conceivable to detect the division for each unit area by reading a flag or a marker embedded in the image data for each unit area or counting the number of codes processed by the unpack unit 11.
The LUT 13 is for specifying the correspondence relationship between the code types constituting the image data to be processed and the number of adaptive clocks for the code types. That is, in the LUT 13, for various types of codes, the value of the number of adaptive clocks of the codes is registered in advance. It is assumed that the code type registered in the LUT 13 corresponds to the type of variable length code used when the image data to be processed is compression encoded. The number of adaptive clocks corresponds to the minimum number of operation clocks in the decompressor 2 that is necessary in order not to delay the processing after the decoding. This value is uniquely determined from the performance.
The number-of-clocks counting unit 14 per unit accumulates the number of clocks specified for each code constituting the image data based on the LUT 13 and delimits the detection result by the unit amount counter 12 so as to delimit each unit area. The number of adaptive clocks is obtained.

  With such a configuration, the clock number detection means 5 in the first embodiment adapts each unit region based on a table that specifies the correspondence between the code types constituting the image data and the number of adaptive clocks of the code types. The number of clocks is detected.

  In FIG. 1, the speed control means 6 controls the processing operation speed in the decompressor 2, that is, the number of operation clocks when the decompressor 2 performs decoding. Specifically, the speed control means 6 changes the number of operation clocks when the decompressor 2 performs decoding for each unit area based on the adaptive clock number detected by the clock number detection means 5. Yes.

Here, the speed control means 6 will be described in more detail.
FIG. 3 is a block diagram showing a configuration example of the speed control means in the decoding apparatus according to the present invention. As shown in the figure, the speed control means 6 described here includes a PLL (Phase Locked Loop) 21, a MUX (multiplexer) 22, and a speed determination unit 23.

The PLL 2 generates a clock signal that the decompressor 2 uses as an operation clock. However, the PLL 2 can generate clock signals having various frequencies such as 1 / n multiplication, 1 multiplication, and n multiplication.
The MUX 22 selects any one of clock signals of various frequencies generated by the PLL 2 and outputs the selected clock signal as an operation clock used by the expander 2 to the expander 2.
The speed determination unit 23 switches the clock signal selected by the MUX 22 for each unit area of the image data to be processed by the decompressor 2 based on the adaptive clock number detected by the clock number detection means 5. Specifically, the speed determination unit 23, based on the number of adaptive clocks for each unit area detected by the clock number detection means 5, “the number of adaptive clocks for each unit area” × “the frequency of the clock signal generated by the PLL 2”. "> The MUX 22 is instructed to select a clock signal having a minimum frequency that satisfies the" data transfer speed required by the printer engine 4 ".

With such a configuration, the speed control means 6 changes the number of operation clocks when the decompressor 2 performs decoding for each unit area of image data to be processed by the decompressor 2. Yes.
In the example illustrated in FIG. 3, the case has been described in which the MUX 22 selects any one of the clock signals having various frequencies generated by the PLL 2. For example, the frequency of the clock signal generated by the PLL 2. It is also conceivable that a frequency value can be appropriately adjusted according to a determination result by the speed determination unit 23 by providing a mechanism that can arbitrarily change the frequency.

In the decoding apparatus configured as described above, the decompressor 2, the clock number detection means 5, and the speed control means 6 are, for example, a dedicated ASIC (Application Specified Integrated Circuit) as described with reference to FIG. 2 or FIG. However, the present invention is not necessarily limited to this, and may be configured by software, such as a printer driver that operates on a computer. . In this case, the software configuration is not installed in the computer, but is provided by being stored in a computer-readable storage medium or via a wired or wireless communication means. May be distributed.
That is, the decoding apparatus having the above-described configuration can be realized by a decoding program for causing a computer to function as a decoding apparatus.

  Next, a processing procedure in the decoding apparatus configured as described above (hereinafter including a decoding apparatus that is also realized by a decoding program), that is, a decoding method according to the present invention will be described.

  In decoding the image data stored in the memory 1, first, the clock number detecting means 5 detects the adaptive clock number for each unit area of the image data. Specifically, by referring to the registered contents of the LUT 13 for each code constituting the image data, the adaptive clock number of the code is specified, and the specified adaptive clock number for one unit region is accumulated. , To obtain the number of adaptive clocks in the unit area.

The unit area at this time may be, for example, a block unit area of a plurality of pixels × a plurality of pixels, a line unit area in which a plurality of pixels are arranged in a line, or a band unit area including a plurality of lines. However, it is assumed that the unit area is set in advance in the unit quantity counter 12 in the clock number detection means 5, for example.
This means that the unit area may be set in any way as long as it can be set in the unit amount counter 12. For example, if the unit area is set small, the number of clocks can be changed finely, but the processing load for the change increases, and if the unit area is set large, the opposite is true.
The unit area is not necessarily limited to a certain amount such as a block unit, a line unit, or a band unit. For example, when the so-called TI separation that separates the text (character) region and the image (image) region in the image data can be performed, the text region and the image region after the separation may be used as a unit region. If the unit area is set in this way, the number of clocks can be suitably changed according to the characteristics of the image.

When the clock number detection unit 5 detects the adaptive clock number for each unit area, the speed control unit 6 then performs decoding of each code in the unit area based on the detection result of the adaptive clock number. The number of operation clocks in the decompressor 2 is controlled. For example, the speed control means 6 reduces the number of operation clocks of the decompressor 2 for the region unit that mainly consists of codes with a short code length and requires less time for decoding. The number of operation clocks of the decompressor 2 is increased for an area unit that consists of codes and requires a long time for decoding.
Then, while following the control by the speed control means 6, the decompressor 2 operates at the number of operation clocks instructed from the speed control means 6, receives the compression-coded image data from the memory 1 and decodes it. To FIFO3.

After that, when the FIFO 3 holds the decoded image data of a certain amount, for example, page unit, the FIFO 3 starts transferring the held image data to the printer engine 4.
At this time, however, the speed control means 6 controls the number of operating clocks in the former stage expander 2 in which the image data is stored in the FIFO 3. That is, it is controlled to the minimum number of operation clocks necessary to prevent delaying the processing after decoding. For this reason, transfer of image data between the decompressor 2 and the printer engine 4 via the FIFO 3 is not delayed. Moreover, even in that case, it is not necessary to increase the frequency of the operation clock signal of the expander 2 more than necessary.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Here, only differences from the above-described first embodiment will be described.

  The second embodiment described here is different from the first embodiment in the number-of-clocks detection means 5. FIG. 4 is a block diagram showing a configuration example of the clock number detection means in the second embodiment of the present invention. As shown in the figure, the clock number detection means 5 described here includes an unpacking unit 11, a unit amount counter 12, a clock number counting unit 14 per unit, and a calculation unit 15. That is, the calculation unit 15 is provided instead of the LUT 13 in the first embodiment.

  The calculation unit 15 calculates the number of adaptive clocks of the code from the code length per symbol of the code constituting the image data to be processed. That is, the arithmetic unit 15 holds an arithmetic expression that specifies the correspondence between the code length per symbol and the number of adaptive clocks of the code, and calculates the adaptive clock number of each code using the arithmetic expression. It is supposed to be. Note that the arithmetic expression held by the arithmetic unit 15 is a relational expression that is uniquely determined from the performance of the decompressor 2, the FIFO 3, and the printer engine 4.

  With such a configuration, in the clock number detection means 5 in the second embodiment, the code constituting the image data is obtained by accumulating the calculation result by the calculation unit 15 by the clock number counting unit 14 per unit area. The number of adaptive clocks for each unit area is detected from the code length per symbol.

  Therefore, also by the decoding apparatus, the decoding program, and the decoding method described in the second embodiment, the decompressor 2 is based on the number of adaptive clocks detected by the clock number detection means 5 as in the case of the first embodiment. By changing the number of operation clocks for decoding for each unit area, for example, even if the image data to be processed is compression-coded using a variable-length code, Decrease the number of operation clocks for region units that consist of data and require less time for decoding, and increase the number of operation clocks for region units that mainly consist of long code length data and require a long time for decoding. It becomes possible.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. Here, only differences from the above-described first or second embodiment will be described.

  The third embodiment described here is also different from the first or second embodiment in the number-of-clocks detection means 5. FIG. 5 is a block diagram showing a configuration example of the clock number detection means in the third exemplary embodiment of the present invention. As shown in the figure, the clock number detection means 5 described here includes an unpacking unit 11, a unit amount counter 12, a clock number counting unit 14 per unit, and an LUT 16. That is, in place of the LUT 13 in the case of the first embodiment, the LUT 16 is provided in the subsequent stage of the clock number counting unit 14 per unit.

  The LUT 16 registers the correspondence relationship between the codes constituting the image data and the number of adaptive clocks in substantially the same manner as the LUT 13 in the first embodiment. The LUT 13 specifies the number of applied clocks for each code type. In contrast to the LUT 13, it is for specifying the number of adaptive clocks per unit area.

With such a configuration, in the clock number detecting means 5 in the third embodiment, the clock number counting unit 14 per unit has the number of symbols, code length, or number of symbols per unit area corresponding to the unit area. And the code length are accumulated, by referring to the registered contents of the LUT 16, the number of adaptive clocks corresponding to at least one of the number of symbols or the code length, that is, the number of adaptive clocks in the unit area is obtained.
Here, the case where the number of adaptive clocks in the unit area is obtained based on the LUT 16 is taken as an example. However, instead of using the LUT 16, the adaptive clock is obtained through arithmetic processing as in the second embodiment. You may make it obtain a number. In any case, whether the number of symbols, the code length, or both of them is based depends on the compression encoding method of the image data to be processed.

  Therefore, also by the decoding apparatus, the decoding program, and the decoding method described in the third embodiment, based on the adaptive clock number detected by the clock number detection unit 5 as in the first or second embodiment. By changing the number of operation clocks when the decompressor 2 performs decoding for each unit region, for example, even when image data to be processed is compression-coded using a variable-length code, it is mainly short. The number of operation clocks is reduced for the region unit consisting of code length data and requiring less time for decoding, and the number of operation clocks for region units consisting mainly of long code length data and requiring much time for decoding. Can be increased.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. Here, only differences from the above-described first to third embodiments will be described.

  The fourth embodiment described here is also different from the first to third embodiments described above in the number-of-clocks detection means 5. FIG. 6 is a block diagram showing a configuration example of the clock number detection means in the fourth exemplary embodiment of the present invention. As shown in the figure, the clock number detection means 5 described here includes a marker detection unit 17 and a clock number detection unit 18.

The marker detection unit 17 detects a predetermined marker or the like embedded in the image data to be processed and reads it from the image data. The predetermined marker or the like read by the marker detection unit 17 is embedded in each unit area of the image data by the encoding device when the image data to be processed is compressed and encoded, for example. Related to information for identifying the number of adaptive clocks in the unit area. However, the detection target by the marker detection unit 17 is not limited to the marker embedded in the image data as long as it relates to information for specifying the number of adaptive clocks, and may be a flag, a header, or the like.
The clock number detection unit 18 specifies an adaptive clock number for each unit area based on a predetermined marker read from the image data by the marker detection unit 17.

  With such a configuration, in the clock number detection means 5 in the fourth embodiment, as long as a predetermined marker or the like is added to the image data to be processed, the LUTs 13 and 16 and the arithmetic unit 15 are prepared in advance. Even if not, it is possible to detect the number of adaptive clocks for each unit area from the image data.

  Therefore, also in the decoding apparatus, the decoding program, and the decoding method described in the fourth embodiment, based on the adaptive clock number detected by the clock number detection unit 5 as in the first to third embodiments. By changing the number of operation clocks when the decompressor 2 performs decoding for each unit region, for example, even when image data to be processed is compression-coded using a variable-length code, it is mainly short. The number of operation clocks is reduced for the region unit consisting of code length data and requiring less time for decoding, and the number of operation clocks for region units consisting mainly of long code length data and requiring much time for decoding. Can be increased.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. Here, only differences from the above-described first to fourth embodiments will be described.

  The fifth embodiment described here is also different from the first to fourth embodiments in the number-of-clocks detection means 5. FIG. 7 is a block diagram showing a configuration example of the clock number detecting means in the fifth embodiment of the present invention. As shown in the figure, the clock number detection means 5 described here detects the adaptive clock number in the decompressor 2 based on the clock number required when the decompressor 2 performs the decoding process. It has become.

  Specifically, in the clock number detection means 5, the number of clocks required when the decompressor 2 has already decoded each code is sequentially accumulated by the clock number counting unit 14 while the result of detection by the unit quantity counter 12 is detected. Is used as a delimiter to obtain the cumulative number of clocks for each unit area. Then, the accumulated clock number is set to the clock number required when the decompressor 2 has already decoded the unit area, and based on this, the adaptive clock number for the unit area decoded by the decompressor 2 after the unit area is obtained. Detect.

  With such a configuration, in the clock number detection means 5 in the fifth embodiment, for example, if it takes a long time for the decompressor 2 to decode a certain unit area, then the unit area to be decoded by the decompressor 2 next. Is given to the speed control means 6 so as to increase the number of operation clocks of the decompressor 2, or for example, if the time required for decoding in the decompressor 2 for a certain unit area is small, the next For the unit area to be decoded by the decompressor 2, it is possible to give an instruction to the speed control means 6 so as to reduce the number of operation clocks of the decompressor 2. That is, the number of adaptive clocks for each unit area is specified so that data transfer to the printer engine 4 is not delayed in the entire image data transfer unit (for example, page unit).

  Therefore, even with the decoding apparatus, decoding program, and decoding method described in the fifth embodiment, the number of operation clocks when the decompressor 2 performs decoding based on the adaptive clock number detected by the clock number detection means 5 Can be changed for each unit area. In other words, even if the LUTs 13 and 16 and the calculation unit 15 are not prepared in advance, or even if a predetermined marker or the like is not added to the image data to be processed, the clock adjustment is performed throughout the transfer unit of the image data. By performing the above, even if the image data to be processed is compression-coded using a variable length code, if the time required for decoding is sufficient, the number of operation clocks of the decompressor 2 is reduced, In addition, when the time required for decoding is not sufficient, the number of operation clocks of the decompressor 2 can be increased.

As described above, according to the decoding apparatus, the decoding program, and the decoding method described in the first to fifth embodiments, decoding is performed based on the number of adaptive clocks in each unit area for each unit area of image data. Thus, for example, by increasing the number of operation clocks for a region unit that requires time, it is possible to prevent data transfer after decompression by the decoding from being delayed. That is, even when image data compressed and encoded using a variable-length code is decoded and decompressed, data transfer after the decompression can be guaranteed. Furthermore, it is possible to reduce the number of operating clocks, for example, for an area unit that requires less time for decoding. This also reduces power consumption when decoding and decompressing image data. Will be able to.
In other words, even if the image data to be processed by the decompressor 2 is compression-coded using a variable length code, the decompression unit 2 cannot keep up with the decoding and waits for the print output by the printer engine 4. It will be possible to avoid the occurrence of such a situation. Therefore, even if the decompressor 2 does not always perform a high-speed operation based on the worst condition, it is possible to easily increase the printer engine 4 and improve the productivity of print output. In addition, even when the productivity of print output is improved, the frequency of the operation clock signal of the decompressor 2 can be reduced as necessary, so that the power consumption can be reduced. Become.

It is a block diagram which shows the schematic structural example of the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the clock number detection means in 1st Embodiment of the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the speed control means in the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the clock number detection means in 2nd Embodiment of the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the clock number detection means in 3rd Embodiment of the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the clock number detection means in 4th Embodiment of the decoding apparatus which concerns on this invention. It is a block diagram which shows the structural example of the clock number detection means in 5th Embodiment of the decoding apparatus which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Memory, 2 ... Decompressor, 3 ... FIFO, 4 ... Printer engine, 5 ... Clock number detection means, 6 ... Speed control means, 11 ... Unpack part, 12 ... Unit quantity counter, 13, 16 ... LUT, 14 ... Clock number counting unit per unit, 15 ... calculation unit, 17 ... marker detection unit, 18 ... clock number detection unit, 21 ... PLL, 22 ... MUX, 23 ... speed determination unit

Claims (18)

A decompressor for receiving and decoding the compression-encoded image data;
A clock number detecting means for detecting the number of clocks adapted for decoding by the decompressor for each unit area of the image data;
A decoding apparatus comprising: speed control means for changing the number of operating clocks for each unit region when the decompressor performs decoding based on the number of clocks detected by the number-of-clocks detection means. The clock number detecting means is a clock adapted to decoding for each unit region based on a table for specifying a correspondence relationship between a code type constituting the image data and a clock number adapted to decoding of the code type. The decoding device according to claim 1, wherein the number is detected. The decoding apparatus according to claim 1, wherein the clock number detection means calculates a clock number adapted to decoding for each unit region from a code length per symbol of a code constituting the image data. . The clock number detection means detects the number of clocks adapted to decoding for each unit region based on at least one of the number of code symbols or code length per unit region. Decryption device. The said clock number detection means detects the clock number which adapts to the decoding for every said unit area | region based on the information added to the image data which the said decompressor received. Decryption device. The clock number detection means detects the number of clocks for a unit area decoded by the decompressor after the unit area based on the number of clocks required when the decompressor has already decoded the unit area. The decoding device according to claim 1. Computer
Decompression means for receiving compression-encoded image data and decoding it;
A clock number detecting means for detecting the number of clocks adapted for decoding by the decompressor for each unit area of the image data;
A decoding program that functions as speed control means for changing the number of operating clocks for each unit region when the decompressor performs decoding based on the number of clocks detected by the clock number detection means. The clock number detecting means is a clock adapted to decoding for each unit region based on a table for specifying a correspondence relationship between a code type constituting the image data and a clock number adapted to decoding of the code type. The decoding program according to claim 7, wherein the number is detected. The decoding program according to claim 7, wherein the clock number detection means calculates a clock number adapted to decoding for each unit region from a code length per symbol of a code constituting the image data. . The said clock number detection means detects the clock number which adapts to the decoding for every said unit area | region based on at least one of the symbol number or code length of the code | symbol per said unit area | region. Decryption program. The said clock number detection means detects the clock number applicable to the decoding for every said unit area | region based on the information added to the image data which the said expansion | extension means received. Decryption program. The number-of-clocks detecting means detects the number of clocks for a unit area decoded by the extension means after the unit area based on the number of clocks required when the extension means has already decoded the unit area. The decoding program according to claim 7. A decoding method for receiving compressed and encoded image data and decoding it with a decompressor,
A clock number detection step for detecting a clock number adapted for decoding by the decompressor for each unit area of the image data;
And a speed control step of changing, for each unit region, the number of operating clocks when the decompressor performs decoding based on the number of clocks detected in the number of clocks detection step. In the clock number detection step, a clock adapted to decoding for each unit region based on a table specifying a correspondence relationship between a code type constituting the image data and a clock number adapted to decoding of the code type The decoding method according to claim 13, wherein the number is detected. The decoding method according to claim 13, wherein, in the clock number detection step, a clock number suitable for decoding for each unit region is calculated from a code length per symbol of a code constituting the image data. . The clock number detection step detects the number of clocks suitable for decoding for each unit region based on at least one of the number of symbols or the code length of the code per unit region. Decryption method. The clock number detection step detects the number of clocks adapted to decoding for each unit area based on information added to the image data received by the decompressor. Decryption method. In the clock number detection step, based on the number of clocks required when the decompressor has already decoded the unit region, the number of clocks for the unit region decoded by the decompressor after the unit region is detected. The decoding method according to claim 13.

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